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From: candycanearter07 <candycanearter07@candycanearter07.nomail.afraid>
Newsgroups: comp.lang.c
Subject: Re: Why is this happening?
Date: Tue, 31 Mar 2026 19:00:03 -0000 (UTC)
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James Kuyper <jameskuyper@alumni.caltech.edu> wrote at 00:37 this Tuesday (GMT):
> On 2026-03-29 16:54, Keith Thompson wrote:
> ...
>> context that doesn't need floating-point.  I'm not sure whether
>> (unsigned long)1e9 is actually guaranteed to yield 1000000000 rather
>> than 999999999.  Maybe it is, but I don't want to waste brain cells
>> proving it.
>
> I'll waste my brain cells.
>
> "When a finite value of decimal floating type is converted to an integer
> type other than bool, the fractional part is discarded (i.e. the value
> is truncated toward zero)." (6.3.2.4p2)
>
> "For decimal floating literals ... the result is either the nearest
> representable value, or the larger or smaller representable value
> immediately adjacent to the nearest representable value, chosen in an
> implementation-defined manner." (6.4.5.3p4)
>
> This allows for 1e9 to have a value of exactly 1000000000.0, or slightly
> higher, which converts to unsigned long as 1000000000, or a value
> slightly less than 1000000000.0, which will convert to 999999999.
>
> So you were right - don't use floating point to do what integer types
> are sufficient to do.


Floats should not be used for any kinda comparisons besides basic
greater than/less than checks or flooring it beforehand, its just too
unreliable.

also languages that make no distinguishment are very frustrating
sometimes
-- 
user <candycane> is generated from /dev/urandom